外源激素与内生真菌互作对醉马草低温胁迫下种子萌发的影响

低温是限制种子萌发的一个关键因子,而外源激素和内生真菌分别通过外部介导和内部调控的途径来提高低温环境下种子的萌发能力.本研究以感染内生真菌(E+)和未感染内生真菌(E-)醉马草(Achnatherum inebrians)种子为材料,利用不同浓度的水杨酸(SA)或脱落酸(ABA)溶液浸泡种子,测定10℃条件下醉马草种子的发芽率、发芽指数、胚芽长、胚根长和幼苗含水量,探讨外源激素与内生真菌互作对醉马草种子低温条件下萌发的影响.结果发现,SA或ABA处理能促进醉马草E+、E-种子的萌发;高浓度SA或ABA处理下则表现出抑制作用,其中高浓度(0.2 mmol/L)ABA对种子发芽抑制作用显著(P<0.05);SA与内生真菌互作对种子发芽率、发芽指数和胚根长有显著(P<0.05)促进作用;ABA与内生真菌互作对种子发芽指数、胚芽长、胚根长和幼苗含水量有显著(P<0.05)的促进作用.表明一定浓度范围的SA或ABA与内生真菌互作,能够促进醉马草种子在低温胁迫条件下的萌发力.     

Determination of the total concentration of casein and β-lactoglobulin by indirect competitive ELISA in milk and dairy products

The main purpose of this work was to develop an assay as a means of quality control in milk and dairy products. As specific and high abundant proteins in milk and diary products, casein and β-lactoglobulin were chosen as the targets, and an indirect competitive enzyme-linked immunosorbent assay （ELISA） was developed for determination of the total concentration of casein and β-lactoglobulin. The detection limit of the assay was 79.07 ng/mL, and a working range of the calibration curve was from 140.6 to 36,000 ng/mL. The intrassay and inter-assay coefficients of variations were 4.7 % and 6.5 %, respectively. The recoveries ranged from 94.1% to 106.6 %. The developed ELISA assay was used to detect the total con- centration of casein and β-lactoglobulin in liquid milk and milk powder. The results indicated that the developed assay was very specific, and the addition of nonprotein nitrogen （such as melamine, cyanuric acid, and urea） and vegetable protein did not affect the detection. The good performance of the assay makes it suitable for use in the quality control of milk and dairy products.     

论有线电视工程验收在有线电视稳定可靠发展建设中的作用

文章详细介绍了有线电视工程验收的几个方面,阐述了如何通过工程验收来保证有线电视可靠稳定发展.     

The effect of water content in crude oil on the tribological behavior of screw pump’s stator rubber

It is worthy of studying the effect of water content in crude oil on tribological behavior of stator rubber, because the different water content would affect the swelling and wear of rubber. Compatibility of dewatered crude oil and water was observed after mixture of dewatered crude oil and water （called oilwater mixture） was mechanical stirred and statically placed. Static etching experiment of samples in oil-water mixture was performed using hanging patch test. Wetting contact angle of oil- water mixture on rubber surface was measured by contact angle meter. Tribological behavior of samples in mixture was measured using a ringonblock tester. The result shows that when the water content is less than 15 %, water can blend with dewatered crude oil, and oil-water separation happens when water content was more than 15 %. With the increasing of water content in crude oil, Wettability of mixture and swelling increment of samples decrease. The wear loss of sample increases after treated by swelling experiment, and FKM owns better wear resistance than NBR.     

Deformation and damage behaviors of as-cast TiAl-Nb alloy during creep

By means of creep properties measurement and microstructure observation,the deformation and damage behavior of an as-cast TiAl-Nb alloy during creep at temperature near 750°C were investigated.The results showed that the microstructure of the alloy consisted of lamellarγ/α_2 phase,and the boundaries consisted ofγphase located in between lamellarγ/α_2 phases with different orientations.In the latter stage of creep,the dislocation networks appeared in the interfaces of lamellarγ/α_2 phases due to the coarsening of them,which made the coherent interface transforming into the semi-coherent one for reducing its adhesive strength.The deformation mechanism of the alloy during creep was twinning and dislocations slipping within lamellarγ/α_2 phases.In the later period of creep,significant amount of dislocations plied up in the interfaces of lamellarγ/α_2 phases,which may cause the stress concentration to promote the initiation and propagation of the cracks along the lamellarγ/α_2interfaces perpendicular to the stress axis.Wherein,some cracks on the various cross-sections were connected by tearing edge along the direction of maximum shear stress,up to the creep fracture,which is considered to be the damage and fracture mechanism of alloy during creep at 750°C.     

重组葡萄糖脱氢酶的表达及辅酶再生应用研究

为解决异源表达酮还原酶域EryKR1的重组大肠杆菌Escherichia coli BL21(pET28a-eryKR1)催化环己酮还原时消耗的氢供体NADPH再生的问题,构建了克隆枯草芽孢杆菌葡萄糖脱氢酶基因gdh的重组菌E.coli BL21(pET28a-gdh),其中的gdh基因经Nucleotide BLAST功能分析显示与枯草芽孢杆菌9902的gdh基因序列(登录号为EF626962.1)的一致性达到100%。SDS-PAGE检测显示该重组菌经IPTG诱导后可以高效表达出葡萄糖脱氢酶(GDH),其表达量占全菌可溶性蛋白质的64%。GDH粗酶液的比酶活为137.90U/mg。通过气相色谱检测添加了E.coli BL21(pET28a-gdh)的E.coli BL21(pET28a-eryKR1)环己酮还原反应体系中的环己醇含量,结果显示加入重组GDH的双重组菌耦合反应体系中环己醇的产率为82.21%,是未添加GDH的反应体系对应值的3.23倍,表明重组GDH可以为EryKR1还原环己酮系统解决辅酶再生问题。     

精炼渣对60Si2Mn弹簧钢中氧含量及夹杂物的影响

利用热力学软件FactSage 7.0计算1873K下四元渣系CaO-SiO_2-Al_2O_3-MgO与60Si2Mn弹簧钢平衡时的等氧线,通过渣-钢高温平衡试验,测定了不同精炼渣方案下钢中溶解氧和全氧含量,并对钢中非金属夹杂物的形貌、数量和尺寸分布进行表征。结果表明,1873K温度下,w(MgO)=6%且w(CaO)/w(Al_2O_3)=1时,钢液中溶解[O]及T[O]含量随着渣中w(SiO_2)的增大而增加,而当w(SiO_2)=30%时,随着w(CaO)/w(Al_2O_3)的增加,钢液中溶解[O]及T[O]含量分别呈降低和升高的趋势,这与钢液中SiO_2的活度有关;不同精炼渣方案得到的钢中,尺寸小于10μm的夹杂物所占比例超过87%,尺寸小于4μm的夹杂物所占比例超过50%,且单位面积夹杂物的数量与钢中T[O]含量的变化趋势一致。与试验结果对比可知,利用热力学软件FactSage 7.0计算钢中溶解氧含量是可行的。     

沥青路面在半正弦荷载下的力学响应

研究轮胎/路面的接触印迹特征及随机荷载作用特点,采用ABAQUS软件构建路面结构三维有限元模型,对半正弦荷载作用下的沥青路面力学响应进行分析。结果表明,半正弦荷载作用下沥青路面的上面层和中面层出现应力应变集中,应力应变值随路面深度的增加而逐渐减小;沥青路面的竖向、横向及纵向应力最大值均出现在上面层,且竖向应力最大,横向应力次之,纵向应力最小;竖向、横向应变最大值出现在上面层,纵向应变最大值出现在上-中面层,且路面结构内部出现反复的纵向拉-压变形,这很可能是沥青路面轮迹带附近材料产生疲劳损坏的根本原因。另外,荷载作用时间和路面温度对沥青路面应变的影响要大于其对应力的影响,路面温度的升高导致应变增大且延迟了残余应变的恢复时间。     

关于高职教育应用型人才培养的思考

为了培养大批合格的高级技术应用型人才,必须转变教育观念,变“知识本位”为“能力本位”,加强教学内容的针对性和实用性,大力培养“双师型”教师,加强实训基地建设以及改革考试制度等。